The present invention relates to a flexible vapor barrier sheet and to insulation products incorporating the vapor barrier sheet. More particularly, the present invention relates to a flexible substrate sheet having a metallized layer and a radiation cured resin layer laminated thereon. The resin layer contains an inorganic pigment and the vapor barrier sheet has fire resistant characteristics. In a preferred embodiment of the present invention, the flexible laminate sheet is secured to one side of an insulation bat to provide a fire resistant insulation product having a low vapor transmission rate, good insulating properties, and a pleasing appearance.
Vapor barrier sheets are commonly used in conjunction with heat insulating materials, such as fiberglass batting, to provide an insulation product used to line the walls and ceilings of buildings to minimize the cost of heating and cooling the interior spaces thereof. It is, of course, highly desirable that insulation products have both insulation and fire resistant characteristics. A commonly employed insulation product comprises a thickness of fiberglass batting sandwiched between two sheets of kraft paper, one of the sheets having a vapor barrier, such as aluminum foil, laminated thereon. In use, insulation products having a foil vapor barrier have certain limitations, however. For example, the vapor barrier characteristics of foil tend to deteriorate as the foil is subjected to flexing or bending forces. Also, the foil presents a mirrorlike surface which is expensive to overcoat should a white or other appearance be desired. In addition, foil made of aluminum or other metal having a low melting point, may melt under the high temperatures incurred during a fire and, hence, provide little resistance to fire.
To overcome some of the limitations of foil vapor barriers, resin coated vinyl vapor barriers have been proposed. Such vapor barriers, however, are generally made by processes which involve the application of flammable solvent-containing resin precursors to a substrate sheet and subsequent curing or polymerizing of the precursor to a resin. Solvent trapped in the resin during the curing step may cause a deterioration of the fire resistant properties of the vapor barrier. In addition, resin coated vinyl vapor barriers may have vapor transmission rates higher than are desired for some uses.
Wherefore, it is an object of the present invention to provide an improved vapor barrier sheet and insulation products incorporating the sheet. It is another object of the present invention to provide a vapor barrier sheet and insulation products having fire resistant features, including resistance to the propagation of flames and generation of smoke. It is also an object of this invention, to provide a vapor barrier sheet having a low vapor transmission rate such as is suitable for use in conjunction with other insulation material in an insulation product, and wherein the vapor transmission rate does not deteriorate when the vapor barrier sheet is bent. Still another object of this invention is to provide a vapor barrier material which can also serve as an infrared or heat reflector. Yet another object of this invention is to provide a vapor barrier sheet having a desirable physical appearance.